. >> reporter: gasia, prosecutors say those bombs placed by dzhokhar tsarnaev and his brother at the boston marathon were weapons of mass destruction that caused death. today the city and the nation also took an important step in the healing process. from the streets of boston, to the capitol in washington, people observed a moment of silence at 2:50 p.m. eastern, exactly one week after two bombs killed three and injured more than 180 others near the finish line of the boston marathon. [ bagpipes ] >> reporter: later, the fbi handed control of boylston street back to the city of boston. from his hospital bed, the 19- year-old suspect, dzhokhar tsarnaev, made his first appearance in front of a magistrate judge. tsarnaev is now charged with conspiring to use a weapon of mass destruction. in addition to the surveillance video the fbi shared with the public, a special agent testified the younger brother, dzhokhar, can be seen apparently slipping his knapsack onto the ground shortly before the explosion. but the white house announced tsarnaev won't be tried in a military tribunal as an en